The first main goal of the proposed experiments is to determine whether interference from irrelevant information, a major source of forgetting in explicit memory, also affects implicit memory. Previous investigations have concluded that implicit memory is immune to interference. However, those investigations contained a potentially important confound: The irrelevant information was not similar to the target memory information in a way that would allow the irrelevant information to compete with the target information as a possible response on the memory test. Competition of this sort is the major source of interference. The proposed experiments will vary the similarity of the irrelevant information to the target information; when the irrelevant information is similar to the target information in a way that will allow competition on the implicit memory test, interference is expected to occur. The second main goal of the proposed experiments is to determine the conditions under which the implicit memory of older adults is more vulnerable than that of young adults to interference. On explicit tests, older adults are more vulnerable to interference from irrelevant items than are young adults because older adults are less able to inhibit the irrelevant information. The proposed experiments will vary the opportunity to inhibit (ignore) irrelevant items; older adults are expected to be less able to inhibit the irrelevant information when given the opportunity to do so, and under these conditions age differences will occur. The results of these experiments will help refine knowledge about the basic systems of memory and when age differences in memory occur, and may aid in the design of interventions to reduce age differences.